lower-ranking vs junior-grade

lower-ranking and junior-grade both are adjectives.

Word	Noun	Adjective	Verb	Adverb
lower-ranking	No	Yes	No	No
junior-grade	No	Yes	No	No

As adjectives, lower-ranking and junior-grade are synonyms defined as:

Other synonyms of lower-ranking include lowly, petty, secondary, subaltern.

lower-ranking (adjective)	junior-grade (adjective)
inferior in rank or status	inferior in rank or status